Fix error from MikroTik routers when updating BGP peer info (#16224)

* Create a case for routeros.

RouterOS doesn't support the bgpPeerInUpdateElapsedTime object, so when
LibreNMS does to insert a peer update into the database from a MikroTik
router, you see the following error:

SQLSTATE[22007]: Invalid datetime format: 1366 Incorrect integer value: '' for column `librenms`.`bgpPeers`.`bgpPeerInUpdateElapsedTime` at row 2 (Connection: mysql, SQL: UPDATE `bgpPeers` set `bgpPeerAdminStatus`=start,`bgpPeerInUpdateElapsedTime`=...

To fix this, special-case routeros and note that the object is not yet
supported.

* Use spaces, not tabs.

* Use set_numeric() to ensure bgpPeerInUpdateElapsedTime is a number.

---------

Co-authored-by: Joe Clarke <jclarke@cisco.com>

includes/polling/bgp-peers.inc.php

@@ -512,6 +512,7 @@ if (! empty($peers)) {
         $peer_data['bgpPeerOutUpdates'] = set_numeric($peer_data['bgpPeerOutUpdates']);
         $peer_data['bgpPeerInTotalMessages'] = set_numeric($peer_data['bgpPeerInTotalMessages']);
         $peer_data['bgpPeerOutTotalMessages'] = set_numeric($peer_data['bgpPeerOutTotalMessages']);
+        $peer_data['bgpPeerInUpdateElapsedTime'] = set_numeric($peer_data['bgpPeerInUpdateElapsedTime']);
 
         $fields = [
             'bgpPeerOutUpdates' => $peer_data['bgpPeerOutUpdates'],